If you are going to be driving on the street with an OD transmission then use the 240 heads and a 4150 carb. If you are going to be racing the car and you want the extra power then use the 270 heads and a Dominator. But the big cam, big carb and big head combo isn't going to be very happy in OD on the freeway. There really isn't any way around this.
Carbureted I agree. EFI can result in the best of both, IMO.